Lua字符串压缩：连续字符的计数编码

local function pack(s)
    local out, run = {}, 1
    for i = 2, #s + 1 do
        local cur = s:sub(i, i)
        if cur ~= s:sub(i - 1, i - 1) then
            out[#out + 1] = s:sub(i - 1, i - 1) .. run
            run = 0
        end
        run = run + 1
    end
    return table.concat(out)
end

local function unpackRle(s)
    local out = {}
    for c, n in s:gmatch("(%a)(%d+)") do
        out[#out + 1] = c:rep(tonumber(n))
    end
    return table.concat(out)
end
local p = getplayerbyname("arch01")
local packed = pack("aaabccccdd")
sendmsg(p, 1, packed .. " 还原 " .. unpackRle(packed))
-- 输出 a3b1c4d2 还原 aaabccccdd